[cfi] Support explicit sections for functions in cfi-icall.

Allow explicit section for indirectly called functions in cfi-icall.
Jumptables for functions in the same type class must be contiguous, so they
always go to the default text section.

Fixes PR25079.

llvm-svn: 266486
diff --git a/llvm/lib/Transforms/IPO/LowerBitSets.cpp b/llvm/lib/Transforms/IPO/LowerBitSets.cpp
index 1798d83..db5bab0 100644
--- a/llvm/lib/Transforms/IPO/LowerBitSets.cpp
+++ b/llvm/lib/Transforms/IPO/LowerBitSets.cpp
@@ -639,8 +639,9 @@
 
   if (OpGlobal->isThreadLocal())
     report_fatal_error("Bit set element may not be thread-local");
-  if (OpGlobal->hasSection())
-    report_fatal_error("Bit set element may not have an explicit section");
+  if (isa<GlobalVariable>(OpGlobal) && OpGlobal->hasSection())
+    report_fatal_error(
+        "Bit set global var element may not have an explicit section");
 
   if (isa<GlobalVariable>(OpGlobal) && OpGlobal->isDeclarationForLinker())
     report_fatal_error("Bit set global var element must be a definition");